我创建了一个处理音频录制/回放的自定义类,并在该类中放入了一个Protocol
。我在UIViewController
类中实现了Protocol
,并为AudioHelper类调用了setDelegate
方法。
我得到了一个编译错误,这与我的init()
有关。不太确定如何摆脱这个错误:
use of 'self' in method call 'setupAudioSession' before super.init initializes self
override init() {
setupAudioSession()
super.init()
}
如何解决此错误?为什么我必须重写init()?
My AudioHelper类
import Foundation
import AVFoundation
class AudioHelper: NSObject, AVAudioRecorderDelegate {
var audioSession: AVAudioSession?
var audioRecorder: AVAudioRecorder?
var delegate: AudioRecorderProtocol?
class var sharedInstance: AudioHelper {
struct Static {
static var instance: AudioHelper?
static var token: dispatch_once_t = 0
}
dispatch_once(&Static.token) {
Static.instance = AudioHelper()
}
return Static.instance!
}
override init() {
setupAudioSession()
super.init()
}
func setDelegate(delegate: AudioRecorderProtocol) {
self.delegate = delegate
}
func setupAudioSession() {
audioSession = AVAudioSession.sharedInstance()
audioSession?.setCategory(AVAudioSessionCategoryPlayAndRecord, error: nil)
audioSession?.setActive(true, error: nil)
}
func createAudioMessageDirectory() {
let fm = NSFileManager.defaultManager()
if !fm.fileExistsAtPath(GlobalVars.kAudioMessageDirectory) {
var error: NSError?
if !fm.createDirectoryAtPath(GlobalVars.kAudioMessageDirectory, withIntermediateDirectories: true, attributes: nil, error: &error) {
println("Unable to create audio message directory: \(error)")
}
}
}
// MARK: Recording
func beginRecordingAudio() {
createAudioMessageDirectory()
var filepath = GlobalVars.kAudioMessageDirectory.stringByAppendingPathComponent("audiofile.aac")
var url = NSURL(fileURLWithPath: filepath)
var recordSettings = [
AVFormatIDKey: kAudioFormatMPEG4AAC,
AVSampleRateKey: 8000.0,
AVNumberOfChannelsKey: 1,
AVEncoderBitRateKey: 12800,
AVLinearPCMBitDepthKey: 16,
AVEncoderAudioQualityKey: AVAudioQuality.Max.rawValue
]
println("Recorded Audio Message Saved: \(url!)")
var error: NSError?
audioRecorder = AVAudioRecorder(URL: url, settings: recordSettings as [NSObject : AnyObject], error: &error)
if error == nil {
if audioRecorder != nil {
audioRecorder!.delegate = self
audioRecorder!.record()
}
}
else {
println(error!.localizedDescription)
}
}
func stopRecordingAudio() {
if audioRecorder != nil {
audioRecorder!.stop()
}
}
func handleRecordAudioButtonLongPressGestureForState(state: UIGestureRecognizerState) {
if state == UIGestureRecognizerState.Ended {
stopRecordingAudio()
delegate?.onRecordAudioStop()
}
else if state == UIGestureRecognizerState.Began {
beginRecordingAudio()
delegate?.onRecordAudioStop()
}
}
func audioRecorderDidFinishRecording(recorder: AVAudioRecorder!, successfully flag: Bool) {
println("Record Audio Success: \(flag)")
delegate?.onRecordAudioFinished()
}
func audioRecorderEncodeErrorDidOccur(recorder: AVAudioRecorder!, error: NSError!) {
println("Record Audio Encode Error: \(error.localizedDescription)")
}
// MARK: Playback
func playAudioMessageFromUrl(messageId: String) {
if let url = NSURL(string: GlobalVars.kUrlAudioMessage + messageId) {
if let data = NSData(contentsOfURL: url) {
var error: NSError? = nil
let audioPlayer = AVAudioPlayer(data: data, error: &error)
if error == nil {
if audioPlayer != nil {
audioPlayer.numberOfLoops = 0
audioPlayer.volume = 1.0
audioPlayer.prepareToPlay()
audioPlayer.play()
}
}
else {
println("Audio playback error: \(error?.localizedDescription)")
}
}
}
}
}
protocol AudioRecorderProtocol {
func onRecordAudioStart()
func onRecordAudioStop()
func onRecordAudioFinished()
}
我的实现协议的UIViewController (去掉无关的代码)
class ChatViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, AudioRecorderProtocol {
let audioHelper = AudioHelper.sharedInstance
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
override func viewDidLoad() {
super.viewDidLoad()
// addDemoMessages()
setupGestureRecognizer()
setupKeyboardObserver()
setupViews()
setupTableView()
audioHelper.setDelegate(self)
}
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
getUsersFromDb()
getMessagesFromDb()
}
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
setCurrentVC()
tableView.reloadData()
if partnerUserId != nil && !db.doesUserExist(partnerUserId!) {
HttpPostHelper.profileGet(userId: partnerUserId!)
}
requestMessagesFromServer()
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
ViewHelper.scrollTableViewToBottom(tableView)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func handleRecordAudioButtonHold(sender: UILongPressGestureRecognizer) {
audioHelper.handleRecordAudioButtonLongPressGestureForState(sender.state)
}
func onRecordAudioStart() {
dispatch_async(dispatch_get_main_queue(), {
ViewHelper.showToast(NSLocalizedString("RECORDING", comment: ""))
self.recordAudioButton.imageView!.image = UIImage(named: "RecordAudioClicked")
})
}
func onRecordAudioStop() {
dispatch_async(dispatch_get_main_queue(), {
self.recordAudioButton.imageView!.image = UIImage(named: "RecordAudio")
})
}
func onRecordAudioFinished() {
HttpPostHelper.messageAudio(partnerUserId: partnerUserId)
}
func playAudioFromUrl(sender: UIButton) {
let messageId = messages[sender.tag].id
audioHelper.playAudioMessageFromUrl(messageId)
}
}
发布于 2015-04-28 03:46:13
只需将其放在super.init()
下。
对象首先需要由超类初始化,然后才能进行自定义初始化。
override init() {
super.init()
setupAudioSession()
}
发布于 2021-06-22 14:50:28
如果您正在使用MVVM模式,并且确实需要在super.init之前调用某个函数,则可以始终将该函数移动到ViewModel并从那里调用它。只需将viewModel作为注入依赖项注入即可。
https://stackoverflow.com/questions/29904537
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